Traffic radar systems utilizing digital signal processing (DSP) have been in use for a number of years. Such a DSP radar is disclosed, for example, in U.S. Pat. No. 5,528,246 (“'246”) owned by Kustom Signals, Inc. In the '246 patent, the radar transforms target return information into the frequency domain and compares the magnitude of a tested target bin to the magnitude of a moving average of a number of bins surrounding the target bin. Typically, a target is qualified if the tested peak is greater than a threshold significantly higher in magnitude than a surrounding moving average. In this manner of processing, radar return signals from very strong targets qualify at the same time as much weaker return signals as long as the returns are above the target threshold level. If too low a threshold level is chosen, noise signals may be processed as targets. If too high a threshold is chosen, a low level target may not be found. After initial processing, information concerning the signal-to-noise levels of the respective bins is not retained.
It would be advantageous in traffic radar systems to determine targets such that strong targets with high magnitude returns qualify very quickly, whereas weak, but consistent, targets qualify more slowly. Another desired improvement in a traffic radar system would be to display signal strength information to the operator regarding the target being tracked, either the accumulated signal-to-noise ratio or the instantaneous signal strength. Capabilities of an improved system could include creating a target signal history for each target, validating the target based on its signal history, correlating the target with other targets in the operator's field of view, and displaying the magnitude of the target signal in association with the target's speed.